Most existing audio codecs perform well on audio signals with specific configurations, such as mono, stereo, etc. However, for other types of audio signals (e.g., an arbitrary number of channels) it is usually necessary to manually rearrange the signal into sub-signals, each of which abides by an allowed configuration, manually allocate the total bit rates among the sub-signals, and then compress the sub-signals with an existing audio codec.
Lack of guidelines in these conventional approaches to signal rearrangement and bit allocation makes things difficult for non-experts and also usually leads to suboptimal performance.